US20170152013A1 - Aircraft side of body joint - Google Patents
Aircraft side of body joint Download PDFInfo
- Publication number
- US20170152013A1 US20170152013A1 US15/432,193 US201715432193A US2017152013A1 US 20170152013 A1 US20170152013 A1 US 20170152013A1 US 201715432193 A US201715432193 A US 201715432193A US 2017152013 A1 US2017152013 A1 US 2017152013A1
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- web
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- taper
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- 150000001875 compounds Chemical class 0.000 claims description 5
- 239000003733 fiber-reinforced composite Substances 0.000 claims description 3
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- 239000000853 adhesive Substances 0.000 description 2
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- 238000005452 bending Methods 0.000 description 1
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- 239000012783 reinforcing fiber Substances 0.000 description 1
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- 229920005989 resin Polymers 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- B64C1/06—Frames; Stringers; Longerons ; Fuselage sections
- B64C1/064—Stringers; Longerons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- B64C1/06—Frames; Stringers; Longerons ; Fuselage sections
- B64C1/061—Frames
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- B64C1/26—Attaching the wing or tail units or stabilising surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C3/00—Wings
- B64C3/18—Spars; Ribs; Stringers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C3/00—Wings
- B64C3/18—Spars; Ribs; Stringers
- B64C3/182—Stringers, longerons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- B64C1/06—Frames; Stringers; Longerons ; Fuselage sections
- B64C1/10—Bulkheads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- B64C2001/0054—Fuselage structures substantially made from particular materials
- B64C2001/0072—Fuselage structures substantially made from particular materials from composite materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
- Y10T156/10—Methods of surface bonding and/or assembly therefor
- Y10T156/1052—Methods of surface bonding and/or assembly therefor with cutting, punching, tearing or severing
- Y10T156/1062—Prior to assembly
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49616—Structural member making
- Y10T29/49622—Vehicular structural member making
Definitions
- a wing assembly of an aircraft may include a central wing box and wings cantilevered from sides of the central wing box.
- the central wing box carries bending loads applied by each wing during flight.
- a “side of body joint” refers to that portion where a wing is joined to the central wing box.
- a typical side of body joint provides a chordwise splice of the wing to the central wing box, and it provides primary attachment of the wing to the aircraft's fuselage.
- an aircraft includes a wing and wing box.
- the wing is joined to the wing box at a side of body joint.
- the wing and the wing box each includes lower skin and a plurality of stringers on the skin. Ends of at least some of the stringers at the side of body joint have a web cutout and a base that is spanwise tapered to a knife edge at the skin.
- an aircraft wing assembly comprises a central wing box, first and second wings, and splice chords for joining the wings to opposite sides of the wing box.
- the central wing box includes lower skin and stringers on the skin.
- Each wing includes lower skin and stringers on the skin.
- At least some stringer terminations have web cutouts and bases that are spanwise tapered to a knife edge at the skin.
- a beam for an aircraft comprises a base and a web.
- the web has a cutout and the base is tapered to a knife edge at an end of the stringer.
- the tapered base extends longitudinally downward from the cutout at an angle between 10 and 15 degrees.
- a method comprises machining an aircraft stringer having a web and a base.
- the machining includes forming a load-redistributing cutout in the web at an end of the stringer, and forming a longitudinal taper in the base at the end of the stringer. The taper goes from full height of the base to a knife edge at an angle between 10 and 15 degrees.
- FIG. 1 is an illustration of an aircraft.
- FIG. 2A is an illustration of an upper side of body joint of an aircraft.
- FIG. 2B is an illustration of a lower side of body joint of an aircraft.
- FIG. 3 is an illustration of loads at issue for skin and stringers in the lower side of body joint.
- FIG. 4 is an illustration of a first example of a stringer having a web cutout and tapered base.
- FIG. 5 is an illustration of a second example of a stringer having a web cutout and tapered base.
- FIG. 6 is an illustration of a third example of a stringer having a web cutout and with overwrap layer on a tapered base.
- FIG. 7 is an illustration of a stringer including a noodle having a tapered base.
- FIG. 8 is an illustration of the tapered base of the stringer of FIG. 7 .
- FIG. 9 is an illustration of a method of fabricating the stringer of FIG. 7 .
- FIG. 10 is an illustration of a bulkhead frame and transverse beam of a fuselage.
- FIG. 1 illustrates an aircraft 110 including a fuselage 120 , a wing assembly 130 , and empennage 140 .
- the wing assembly 130 includes a central wing box 132 and wings 134 cantilevered from opposite sides of the central wing box 132 .
- the central wing box 132 carries loads applied by each wing 134 during flight.
- the central wing box 132 may also provide other functions, such as storing a central fuel tank, and providing a well for landing gear.
- the central wing box 132 and the wings 134 each include front and rear spars extending in a spanwise direction, ribs extending between the spars in a chordwise direction, upper and lower skin covering the spars and ribs, and upper and lower stringers for stiffening the upper and lower skin.
- the stringers also extend in a spanwise direction.
- FIGS. 2A and 2B illustrate an example of a side of body joint.
- FIG. 2A illustrates an upper portion of the side of body joint (the “upper side of body joint”)
- FIG. 2B illustrates a lower portion of the side of body joint (the “lower side of body joint”).
- the upper side of body joint is compression-critical
- the lower side of body joint is tension-critical.
- the upper and lower joints may be connected by side of body ribs.
- the upper side of body joint 210 includes a splice chord 220 .
- Upper wing skin 232 and upper stringers 234 of a wing 134 are fastened to an outboard side of the splice chord 220 .
- Upper wing skin 236 and upper stringers 238 of the central wing box 132 are fastened to an inboard side of the splice chord 220 .
- the splice chord 220 is also fastened to skin 222 of the fuselage 120 and also to a side of body rib 245 .
- the lower side of body joint 250 includes the splice chord 220 .
- Lower wing skin 242 and lower stringers 244 of the wing 134 are fastened to the outboard side of the splice chord 220 .
- Lower wing skin 246 and lower stringers 248 of the central wing box 132 are fastened to the inboard side of the splice chord 220 .
- cap flanges hereinafter “caps” 244 a and 248 a of the lower stringers 244 and 248 are fastened to the splice chord 220
- the lower skin 242 , 246 is fastened to the splice chord 220 .
- An external splice plate 260 may also be used to fasten the lower skin 242 , 246 to the splice chord 220 .
- Base flanges (hereinafter “bases”) 244 b and 248 b of the lower stringers 244 , 248 are joined (e.g., fastened, bonded) to the lower skin 242 , 246 . There is a gap between the end of each base 244 b and the splice chord 220 , and there is a gap between the end of each base 248 b and the splice chord 220 .
- the lower stringer 244 in the wing 134 includes a web 244 c between its cap 244 a and base 244 b.
- the end of the web 244 c has a web cutout 244 d, and the end of the base 244 b is spanwise tapered to a knife edge at the lower wing skin 242 .
- the lower stringer 248 in the central wing box 132 includes a web 248 c between its cap 248 a and base 248 b.
- the end of the web 248 c has a cutout 248 d, and the end of the base 248 b is spanwise tapered to a knife edge at the lower skin 246 .
- the tapered bases 244 b and 248 b transfer loads more gradually from the lower stringers 244 and 248 into the lower skin 242 and 246 to reduce the abrupt geometric discontinuities across the stringer ends.
- the tapered bases 244 b and 248 b prevent delamination of the lower stringers 244 , 248 from the lower skin 242 , 246 .
- the web cutout 244 d in the lower stringer 244 of the wing 134 performs a different role than the web cutout 248 d in the lower stringer 248 of the central wing box 132 . Due to a difference in centroid alignment between both the wing side and the wing box side, the loads tend to be redistributed differently, causing secondary moments at the stringer termination as well as the stringer cap.
- the web cutouts 244 d in the lower stringers 244 of the wing 134 redistribute vertical pulloff loads.
- the web cutouts 248 d in the lower stringers 248 of the central wing box 132 place the stringer base ends in compression, which keeps those lower stringers 248 from peeling from the lower skin 246 .
- the web cutouts 244 d in the lower stringers 244 of the wing 134 may have different shapes than the cutouts 248 d in the lower stringers 248 of the central wing box 132 .
- FIGS. 2A and 2B illustrate only a single upper stringer 234 and a single lower stringer 244 for the wing 134 , and only a single upper stringer 238 and a single lower stringer 248 for the central wing box 132 .
- the wing 134 includes additional upper and lower stringers 234 and 244 spaced apart along the chordwise direction
- the central wing box 132 includes additional upper and lower stringers 238 and 248 spaced apart along the chordwise direction.
- Some or all of the lower stringers 244 in the wing 134 , and some or all of the lower stringers 248 in the central wing box 132 may have the web cutout and tapered base. One or both of these features may be excluded from a stringer 244 or 248 where appropriate.
- the splice chord 220 in the lower side of body joint 250 is not limited to a double plus chord type.
- the splice chord 220 could be a one-piece plus chord or a T chord.
- FIG. 3 illustrates the loads at issue for the lower skin 242 and stringer 244 at the lower side of body joint 250 for the wing 134 .
- Total stringer axial load is split between a tab 223 of the splice chord (load Ru_a) and the skin 242 (load RI_a).
- the primary mechanism for disband in the bondline between the skin 242 and the stringer 244 is local eccentricity developed in the stringer termination.
- the tapered base 244 b helps to manage the local eccentricity at the bondline.
- a moment (Mss) developed from single shear eccentricity of the tab 223 attachment is the primary source for vertical pulloff loads in the web 244 c.
- the web cutout 244 d reduces the peak vertical pulloff loads by redistributing the loads in the stringer web 244 c.
- the web cutout is not limited to any particular geometry, so long as the web cutout extends beyond the end of the base. Curvature of the cutout may be simple or compound. Different cutouts having simple curvature are illustrated in FIGS. 4 and 5 .
- FIG. 4 illustrates a first example of a stringer 410 having a tapered base 420 and a web 430 with a cutout 440 .
- This type of cutout 440 may be referred to as a “fishmouth” cutout.
- the taper of the base 420 starts from the cutout 440 and terminates in a knife edge 450 .
- This stringer 410 may be used in either the wing or wing box.
- FIG. 5 illustrates a second example of a stringer 510 including a tapered base 520 and a web 530 having a web cutout 540 .
- the web cutout 540 is roughly semicircular.
- the taper of the base 520 does not start at the web cutout 540 .
- the web 530 drops down from the web cutout 540 to a full height base.
- the taper of the base 520 starts from the full height and terminates in a knife edge 550 .
- This stringer 510 may be used in either the wing or wing box.
- the curvature is not limited to the simple curvature illustrated in FIGS. 4 and 5 .
- Other examples of a simple curvature include, but are not limited to, concave and parabolic curvature.
- the curvature may be compound.
- An example of a web cutout having a compound curvature is provided in assignee's US Publication 20110284693.
- FIG. 4 defines the angle of the taper as the angle (a) formed by the tapered surface 420 a and the lower surface 420 b of the tapered base 420 .
- the angle (a) of the taper is not limited to any particular angle. However, the applicants have found that an angle (a) between 10 and 15 degrees is most effective at reducing eccentricities across a stringer termination.
- the taper is not limited to a straight taper. In some embodiments, the taper may be radiused or compound.
- the tapered bases of the stringers in the wing may have different angles than the tapered bases of the stringers in the central wing box. In other embodiments, the angles may be the same.
- FIG. 6 illustrates another example of a stringer 610 having a tapered base 620 and a web 630 with a cutout 640 .
- an overwrap layer 650 is bonded to the tapered surface of the tapered base 620 .
- the overwrap layer 650 may be made of sheet metal or plies of reinforcing fibers that are pre-impregnated with resin.
- the overwrap layer 650 may cover the entire tapered surface of a substantial portion thereof.
- the overwrap layer 650 functions to constrain the end of the tapered base 620 from peeling off the skin.
- the stringers are not limited to any particular cross-section.
- the stringers have an I-shaped or T-shaped cross-section.
- FIG. 7 illustrates a cross-section of an example of a stringer 710 having a cap 715 , tapered base 720 (the taper is not shown), and a web 730 with a cutout (the cutout is not shown).
- the stringer 710 of FIG. 7 has an I-shaped cross-section, which is formed by back-to-back C-channel beams 740 . Webs of the beams 740 may be bonded together by adhesive. Cap flanges of the beams 740 may be bonded to a cap plate 750 to form the cap 715 , and base flanges of the beams 740 may be bonded to a base plate 760 to form the base 720 .
- the stringer 710 further includes structures known as “noodles.”
- a cap noodle 770 is filler material between the radiused portions of the cap flanges
- a base noodle 780 is filler material between the radiused portions of the base flanges.
- the end of the base noodle 780 conforms to the taper of the base 720 (the taper of the base noodle 780 is not shown in FIG. 7 ).
- FIG. 8 illustrates the tapered base 720 of the stringer 710 (looking down on the tapered surface 720 a of the tapered base 720 ).
- Corner ends 725 of the tapered base 720 are rounded or filleted. The rounded or filleted corner ends 725 prevent cracks from initiating and causing disbanding of the stringer 710 from the skin.
- FIG. 9 illustrates a method of fabricating the stringer 710 of FIG. 7 .
- the C-channel beams 740 , cap and base plates 750 and 760 , and cap and base noodles 770 and 780 are bonded together to form an I-beam.
- These elements 740 - 780 may be made of metal, fiber-reinforced composite, or a combination of the two.
- the web cutout is formed, and an end of the base 720 is tapered, for example, by machining.
- the base noodle 780 is also tapered.
- the end corners 725 of the tapered base 720 may be machined so as to be rounded or filleted.
- an overwrap layer is bonded to the tapered surface.
- fabric for plies of the overwrap layer is cut, and adhesive is placed between the tapered surface of the base flange and a faying surface of the uncured overwrap layer.
- the stringer 710 including the overwrap layer, is heated under pressure.
- a wing assembly herein is not limited to a central wing box.
- the use of the web cutout and tapered base may be beneficial for stringers subject to high pull-off loads.
- the wings of the wing assembly may have a dihedral and sweep.
- a wing assembly herein is not so limited.
- a stringer herein is not limited to a wing assembly. Stringers having tapered bases and web cutouts may also be used in the empennage and fuselage of an aircraft.
- the empennage 140 includes horizontal and vertical stabilizers 142 and 144 .
- Each stabilizer 142 and 144 includes a torsion box and at least one wing joined to the torsion box.
- the wing and the torsion box each includes skin and a plurality of stringers on the skin. Ends of at least some of the stringers at wing-torsion box joint have a web cutout and a tapered base.
- FIG. 10 illustrates a fuselage 120 including a bulkhead frame 1010 and transverse beam 1020 . Additional bulkhead frames 1010 and transverse beams 1020 of the fuselage 120 are not illustrated. A pressure deck 1030 is fastened to the transverse beams 1020 .
- Each transverse beam 1020 is joined to a bulkhead frame 1010 by a cap fitting 1050 . Caps of the bulkhead frame 1010 and the transverse beam 1020 are fastened to the cap fitting 1050 . The base of the transverse beam 1020 is fastened to a base fitting 1060 .
- the transverse beam 1020 is shown as having a cutout 1022 and a tapered base 1024 .
Abstract
Description
- A wing assembly of an aircraft may include a central wing box and wings cantilevered from sides of the central wing box. The central wing box carries bending loads applied by each wing during flight.
- A “side of body joint” refers to that portion where a wing is joined to the central wing box. A typical side of body joint provides a chordwise splice of the wing to the central wing box, and it provides primary attachment of the wing to the aircraft's fuselage.
- Due to the importance of this joint, and due to complex loading on it during flight, a robust design is highly desirable.
- According to an embodiment herein, an aircraft includes a wing and wing box. The wing is joined to the wing box at a side of body joint. The wing and the wing box each includes lower skin and a plurality of stringers on the skin. Ends of at least some of the stringers at the side of body joint have a web cutout and a base that is spanwise tapered to a knife edge at the skin.
- According to another embodiment herein, an aircraft wing assembly comprises a central wing box, first and second wings, and splice chords for joining the wings to opposite sides of the wing box. The central wing box includes lower skin and stringers on the skin. Each wing includes lower skin and stringers on the skin. At least some stringer terminations have web cutouts and bases that are spanwise tapered to a knife edge at the skin.
- According to another embodiment herein, a beam for an aircraft comprises a base and a web. The web has a cutout and the base is tapered to a knife edge at an end of the stringer. The tapered base extends longitudinally downward from the cutout at an angle between 10 and 15 degrees.
- According to another embodiment herein, a method comprises machining an aircraft stringer having a web and a base. The machining includes forming a load-redistributing cutout in the web at an end of the stringer, and forming a longitudinal taper in the base at the end of the stringer. The taper goes from full height of the base to a knife edge at an angle between 10 and 15 degrees.
- These features and functions may be achieved independently in various embodiments or may be combined in other embodiments. Further details of the embodiments can be seen with reference to the following description and drawings.
-
FIG. 1 is an illustration of an aircraft. -
FIG. 2A is an illustration of an upper side of body joint of an aircraft. -
FIG. 2B is an illustration of a lower side of body joint of an aircraft. -
FIG. 3 is an illustration of loads at issue for skin and stringers in the lower side of body joint. -
FIG. 4 is an illustration of a first example of a stringer having a web cutout and tapered base. -
FIG. 5 is an illustration of a second example of a stringer having a web cutout and tapered base. -
FIG. 6 is an illustration of a third example of a stringer having a web cutout and with overwrap layer on a tapered base. -
FIG. 7 is an illustration of a stringer including a noodle having a tapered base. -
FIG. 8 is an illustration of the tapered base of the stringer ofFIG. 7 . -
FIG. 9 is an illustration of a method of fabricating the stringer ofFIG. 7 . -
FIG. 10 is an illustration of a bulkhead frame and transverse beam of a fuselage. - Reference is made to
FIG. 1 , which illustrates anaircraft 110 including afuselage 120, awing assembly 130, andempennage 140. In some embodiments, such as the embodiment illustrated inFIG. 1 , thewing assembly 130 includes acentral wing box 132 andwings 134 cantilevered from opposite sides of thecentral wing box 132. Thecentral wing box 132 carries loads applied by eachwing 134 during flight. Thecentral wing box 132 may also provide other functions, such as storing a central fuel tank, and providing a well for landing gear. - The
central wing box 132 and thewings 134 each include front and rear spars extending in a spanwise direction, ribs extending between the spars in a chordwise direction, upper and lower skin covering the spars and ribs, and upper and lower stringers for stiffening the upper and lower skin. The stringers also extend in a spanwise direction. - Each
wing 134 is joined to thecentral wing box 132 at a side of body joint.FIGS. 2A and 2B illustrate an example of a side of body joint.FIG. 2A illustrates an upper portion of the side of body joint (the “upper side of body joint”), andFIG. 2B illustrates a lower portion of the side of body joint (the “lower side of body joint”). The upper side of body joint is compression-critical, and the lower side of body joint is tension-critical. As thewing 134 bends upward, elements of the upper side ofbody joint 210 are forced together, while elements in thelower joint 250 are pulled apart. The upper and lower joints may be connected by side of body ribs. - Referring to
FIG. 2A , the upper side ofbody joint 210 includes asplice chord 220.Upper wing skin 232 andupper stringers 234 of awing 134 are fastened to an outboard side of thesplice chord 220.Upper wing skin 236 andupper stringers 238 of thecentral wing box 132 are fastened to an inboard side of thesplice chord 220. Thesplice chord 220 is also fastened toskin 222 of thefuselage 120 and also to a side ofbody rib 245. - Referring to
FIG. 2B , the lower side ofbody joint 250 includes thesplice chord 220.Lower wing skin 242 andlower stringers 244 of thewing 134 are fastened to the outboard side of thesplice chord 220.Lower wing skin 246 andlower stringers 248 of thecentral wing box 132 are fastened to the inboard side of thesplice chord 220. In the example illustrated inFIG. 2B , cap flanges (hereinafter “caps”) 244 a and 248 a of thelower stringers splice chord 220, and thelower skin splice chord 220. Anexternal splice plate 260 may also be used to fasten thelower skin splice chord 220. - Base flanges (hereinafter “bases”) 244 b and 248 b of the
lower stringers lower skin splice chord 220, and there is a gap between the end of each base 248 b and thesplice chord 220. - The
lower stringer 244 in thewing 134 includes aweb 244 c between itscap 244 a andbase 244 b. The end of theweb 244 c has aweb cutout 244 d, and the end of the base 244 b is spanwise tapered to a knife edge at thelower wing skin 242. - The
lower stringer 248 in thecentral wing box 132 includes aweb 248 c between itscap 248 a andbase 248 b. The end of theweb 248 c has acutout 248 d, and the end of the base 248 b is spanwise tapered to a knife edge at thelower skin 246. - The tapered
bases lower stringers lower skin bases lower stringers lower skin - The
web cutout 244 d in thelower stringer 244 of thewing 134 performs a different role than theweb cutout 248 d in thelower stringer 248 of thecentral wing box 132. Due to a difference in centroid alignment between both the wing side and the wing box side, the loads tend to be redistributed differently, causing secondary moments at the stringer termination as well as the stringer cap. Theweb cutouts 244 d in thelower stringers 244 of thewing 134 redistribute vertical pulloff loads. Theweb cutouts 248 d in thelower stringers 248 of thecentral wing box 132 place the stringer base ends in compression, which keeps thoselower stringers 248 from peeling from thelower skin 246. Since theseweb cutouts web cutouts 244 d in thelower stringers 244 of thewing 134 may have different shapes than thecutouts 248 d in thelower stringers 248 of thecentral wing box 132. -
FIGS. 2A and 2B illustrate only a singleupper stringer 234 and a singlelower stringer 244 for thewing 134, and only a singleupper stringer 238 and a singlelower stringer 248 for thecentral wing box 132. However, thewing 134 includes additional upper andlower stringers central wing box 132 includes additional upper andlower stringers lower stringers 244 in thewing 134, and some or all of thelower stringers 248 in thecentral wing box 132 may have the web cutout and tapered base. One or both of these features may be excluded from astringer - The
splice chord 220 in the lower side of body joint 250 is not limited to a double plus chord type. For example, thesplice chord 220 could be a one-piece plus chord or a T chord. -
FIG. 3 illustrates the loads at issue for thelower skin 242 andstringer 244 at the lower side of body joint 250 for thewing 134. Total stringer axial load is split between atab 223 of the splice chord (load Ru_a) and the skin 242 (load RI_a). The primary mechanism for disband in the bondline between theskin 242 and thestringer 244 is local eccentricity developed in the stringer termination. The taperedbase 244 b helps to manage the local eccentricity at the bondline. A moment (Mss) developed from single shear eccentricity of thetab 223 attachment is the primary source for vertical pulloff loads in theweb 244 c. Theweb cutout 244 d reduces the peak vertical pulloff loads by redistributing the loads in thestringer web 244 c. - The web cutout is not limited to any particular geometry, so long as the web cutout extends beyond the end of the base. Curvature of the cutout may be simple or compound. Different cutouts having simple curvature are illustrated in
FIGS. 4 and 5 . - Reference is now made to
FIG. 4 , which illustrates a first example of astringer 410 having a taperedbase 420 and aweb 430 with acutout 440. This type ofcutout 440 may be referred to as a “fishmouth” cutout. The taper of the base 420 starts from thecutout 440 and terminates in aknife edge 450. Thisstringer 410 may be used in either the wing or wing box. - Reference is now made to
FIG. 5 , which illustrates a second example of astringer 510 including a taperedbase 520 and aweb 530 having aweb cutout 540. Theweb cutout 540 is roughly semicircular. In this example, the taper of thebase 520 does not start at theweb cutout 540. Rather, theweb 530 drops down from theweb cutout 540 to a full height base. The taper of the base 520 starts from the full height and terminates in aknife edge 550. Thisstringer 510 may be used in either the wing or wing box. - The curvature is not limited to the simple curvature illustrated in
FIGS. 4 and 5 . Other examples of a simple curvature include, but are not limited to, concave and parabolic curvature. - In some embodiments, the curvature may be compound. An example of a web cutout having a compound curvature is provided in assignee's US Publication 20110284693.
- Reference is once again made to
FIG. 4 , which defines the angle of the taper as the angle (a) formed by the taperedsurface 420 a and thelower surface 420 b of the taperedbase 420. The angle (a) of the taper is not limited to any particular angle. However, the applicants have found that an angle (a) between 10 and 15 degrees is most effective at reducing eccentricities across a stringer termination. - The taper is not limited to a straight taper. In some embodiments, the taper may be radiused or compound.
- In some embodiments, the tapered bases of the stringers in the wing may have different angles than the tapered bases of the stringers in the central wing box. In other embodiments, the angles may be the same.
- Reference is now made to
FIG. 6 , which illustrates another example of astringer 610 having a taperedbase 620 and aweb 630 with acutout 640. In this example, however, anoverwrap layer 650 is bonded to the tapered surface of the taperedbase 620. Theoverwrap layer 650 may be made of sheet metal or plies of reinforcing fibers that are pre-impregnated with resin. Theoverwrap layer 650 may cover the entire tapered surface of a substantial portion thereof. Theoverwrap layer 650 functions to constrain the end of the taperedbase 620 from peeling off the skin. - The stringers are not limited to any particular cross-section. For example, the stringers have an I-shaped or T-shaped cross-section.
- Reference is now made to
FIG. 7 , which illustrates a cross-section of an example of a stringer 710 having a cap 715, tapered base 720 (the taper is not shown), and aweb 730 with a cutout (the cutout is not shown). The stringer 710 ofFIG. 7 has an I-shaped cross-section, which is formed by back-to-back C-channel beams 740. Webs of thebeams 740 may be bonded together by adhesive. Cap flanges of thebeams 740 may be bonded to acap plate 750 to form the cap 715, and base flanges of thebeams 740 may be bonded to a base plate 760 to form thebase 720. The stringer 710 further includes structures known as “noodles.” Acap noodle 770 is filler material between the radiused portions of the cap flanges, and abase noodle 780 is filler material between the radiused portions of the base flanges. The end of thebase noodle 780 conforms to the taper of the base 720 (the taper of thebase noodle 780 is not shown inFIG. 7 ). - Additional reference is now made to
FIG. 8 , which illustrates the taperedbase 720 of the stringer 710 (looking down on thetapered surface 720 a of the tapered base 720). Corner ends 725 of the taperedbase 720 are rounded or filleted. The rounded or filleted corner ends 725 prevent cracks from initiating and causing disbanding of the stringer 710 from the skin. - Reference is now made to
FIG. 9 , which illustrates a method of fabricating the stringer 710 ofFIG. 7 . Atblock 910, the C-channel beams 740, cap andbase plates 750 and 760, and cap andbase noodles - At
block 920, the web cutout is formed, and an end of thebase 720 is tapered, for example, by machining. During the tapering of thebase 720, thebase noodle 780 is also tapered. In addition, theend corners 725 of the taperedbase 720 may be machined so as to be rounded or filleted. - At
block 930, an overwrap layer is bonded to the tapered surface. For example, fabric for plies of the overwrap layer is cut, and adhesive is placed between the tapered surface of the base flange and a faying surface of the uncured overwrap layer. The stringer 710, including the overwrap layer, is heated under pressure. - A wing assembly herein is not limited to a central wing box. The use of the web cutout and tapered base may be beneficial for stringers subject to high pull-off loads.
- The wings of the wing assembly may have a dihedral and sweep. However, a wing assembly herein is not so limited.
- A stringer herein is not limited to a wing assembly. Stringers having tapered bases and web cutouts may also be used in the empennage and fuselage of an aircraft.
- With reference once again to
FIG. 1 , theempennage 140 includes horizontal andvertical stabilizers stabilizer - Reference is now made to
FIG. 10 , which illustrates afuselage 120 including abulkhead frame 1010 andtransverse beam 1020. Additional bulkhead frames 1010 andtransverse beams 1020 of thefuselage 120 are not illustrated. Apressure deck 1030 is fastened to thetransverse beams 1020. - Each
transverse beam 1020 is joined to abulkhead frame 1010 by acap fitting 1050. Caps of thebulkhead frame 1010 and thetransverse beam 1020 are fastened to thecap fitting 1050. The base of thetransverse beam 1020 is fastened to abase fitting 1060. Thetransverse beam 1020 is shown as having acutout 1022 and a taperedbase 1024.
Claims (22)
Priority Applications (1)
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US15/432,193 US10717511B2 (en) | 2013-08-09 | 2017-02-14 | Aircraft side of body joint |
Applications Claiming Priority (2)
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US13/962,974 US10479475B2 (en) | 2013-08-09 | 2013-08-09 | Composite stringer beam joint structure of an aircraft |
US15/432,193 US10717511B2 (en) | 2013-08-09 | 2017-02-14 | Aircraft side of body joint |
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US13/962,974 Division US10479475B2 (en) | 2013-08-09 | 2013-08-09 | Composite stringer beam joint structure of an aircraft |
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US20170152013A1 true US20170152013A1 (en) | 2017-06-01 |
US10717511B2 US10717511B2 (en) | 2020-07-21 |
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US13/962,974 Active 2033-11-13 US10479475B2 (en) | 2013-08-09 | 2013-08-09 | Composite stringer beam joint structure of an aircraft |
US15/432,193 Active 2034-12-06 US10717511B2 (en) | 2013-08-09 | 2017-02-14 | Aircraft side of body joint |
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US13/962,974 Active 2033-11-13 US10479475B2 (en) | 2013-08-09 | 2013-08-09 | Composite stringer beam joint structure of an aircraft |
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EP (1) | EP2835310B1 (en) |
JP (1) | JP6468749B2 (en) |
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CN (1) | CN104340356B (en) |
CA (1) | CA2850791C (en) |
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Also Published As
Publication number | Publication date |
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ES2678083T3 (en) | 2018-08-08 |
CA2850791C (en) | 2016-06-21 |
US10717511B2 (en) | 2020-07-21 |
RU2014132455A (en) | 2016-02-27 |
US20150041589A1 (en) | 2015-02-12 |
EP2835310B1 (en) | 2018-04-18 |
KR20150018364A (en) | 2015-02-23 |
CA2850791A1 (en) | 2015-02-09 |
JP6468749B2 (en) | 2019-02-13 |
KR102143251B1 (en) | 2020-08-11 |
EP2835310A1 (en) | 2015-02-11 |
RU2671453C2 (en) | 2018-10-31 |
CN104340356B (en) | 2018-06-05 |
US10479475B2 (en) | 2019-11-19 |
JP2015036294A (en) | 2015-02-23 |
CN104340356A (en) | 2015-02-11 |
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